Arc lamp



June 30, 1931. H. J. BRUNK ARC LAMP Filed Sept. 28, 1927 3 sheets-sheet 2 $9 h k H g a l 1 "29 i 30 L 2/11/0655 I XPMI June 30, 1931. H. J. BRUNK ARC LAMP Filed Sept. 28, 1927 3 Sheets$heet 3 Patented June 30, 1931 UNITED STATES PATENT OFFICE HAROLD J. BRUN K, OF CHICAGO, ILLINOIS, ASSIGNOR, BY KESN E ASSIGNMENTS, TO THE C. F. PEASE COMPANY, A. CORPORATION OF DELAWARE ABC LAMP Application filed September 28, 1927. Serial No. 222,537.

This invention relates to improvements in arc lamps.

The principal object of the invention is to provide an improved arc lamp adapted for general illumination and having also as one field of usefulness photographic work, such asblue printing, photo engraving and the like, and as another field of usefulness, therapeutic work.

In arc lamps as at present constructed, trouble is encountered as for example in blue printing, photo engraving and other photographic work, due to the fact that as the carbons are consumed the current decreases,

thus lowering the temperature of the arc and changing the character of the light emitted by decreasing the actinic rays. Also the light flickers under these conditions and when the arc elongates to the breaking point, the light 20 is, of course, completely extinguished momentarily. Further diiiiculty is caused by the tendency of the so called hot spots of the carbons to travel around the points of the carbons thereby causing variations in light and sometimes causing slight shadows to fall over the sensitized photographic material, thus rendering the work of a variable quality and the exposure more or less subject to guess work.

A further object of the invention is to overcome these difliculties by providing mechanism which will so regulate the movable or upper carbon as to prevent the breaking and sputtering of the arc and to stabilize the same.

An additional object is to provide an arc lamp, the movable parts of which operate with so little friction and of such uniform degree in nearly all positions that the lamp may be operated satisfactorily at a considerable angle from the vertical.

Further objects relate to various features of construction and arrangement of parts which will become apparent from a consideration of the following specification and accompanying drawings, wherein Fig. 1 is a front elevation of an arc lamp embodying the present improvements;

Fig. 2 is a side elevation thereof;

Fig. 3 is a top plan view of the upper mechanism;

Fig. 4 is a diagrammatic view illustrating the circuits employed in carrying out the improvements; and

Fig. 5 is atop plan view of the stabilizing ma et and associated parts.

11 the drawings, is a suitable arc lamp frame having a suitable carbon holding member 11 at the bottom thereof for sup porting the carbon 12. An upper carbon 13 is carried by a suitable clutch member indicated generally by the numeral 14 having a buffer spring 15 and a porcelain slide 16, which is guided in its vertical movement by the. guides 17. The above described structure may be of standard construction and forms no part per se of the present improvements.

Suitably carried by the frame 10 is an auxiliary frame 18, having a plurality of lugs 19 suitably spaced along the semi-circular upper ed e 20.

ecured to the four right hand lugs, as viewed in Fig. 1, are a plurality of current responsive coils or coil sections 21. As shown in Fig. 5, these coils are connected with the main conductors 22 in series with the carbons and with the magnet coil 23 and with a suitable resistance 24.

A plurality of high resistance coils 25 are mounted on the left hand row of lugs in Fig. 1 and are shunted across the main line as shown in Fig. 5. The coils or solenoids 21 and 25 are stationary and have open centers through which an arcuate armature or core 26 is adapted to pass. Said armature is carried by a suitable pivoted frame 27 journalled at 2828, to a vertical standard 29. The frame 27 also carries a counter balance 30 on a threaded spindle 31 for counter balancing the Weight of the parts which are very nicely balanced and which turn with very little friction about the two journals.

The upper carbon is raised and lowered by the swinging movement of the frame 27 by means of a cross rod. 32 on which is pivoted a depending bracket 33 at the lower end of which is an angularly disposed arm or clutch 34 with the usual ring at one end surrounding the upper carbon.

It will be seen that as the armature 26 moves through the coils, the frame 27 will be rocked upon the pivots 2828, thereby raising or lowering the bracket and clutch, and thus moVing the upper carbon 13, which, together with the lower carbon 12 is preferably enclosed in a suitable globe 35. The parts are so balanced that the weight of the upper carbon is the only weight supported by the pivoted frame.

In operation, the series coils 21 tend to move the armature in a clock-wise direction, as viewed in Fig. 1, to raise the upper carbon, while the shunt coils 25 tend to move the armature in counter clock-wise directionto lower it. Assuming that no current is flowing and that the carbons are in contact, the immediate efiect of turning on the current is to energize the series coil and raise the upper carbon a certain amount, thus establishing the normal are. As the carbon points are consumed, the length of the arc is increased, its resistance also is increased with a resultant decrease of current in the series coil and an increase in the voltage across the arc.

Considering first the action of the series coils alone, a decrease of current therein will weaken them causing them to tend to decrease their pull on the core and on the upper carbon but nevertheless tending coninually to raise said upper'carbon. When this diminishing upward pull is eventually overcome by an increasingly effective weight, as in the prior practice, the carbon is lowered by said weight but the inertia of the weightfrequently lowers the carbon to such a point that the clutch releases it and it drops, thus extinguishing the arc.

Considering the action of the shunt coils, as in the present case where the weight is dispensed with, as the normal arc lengthens due to consumption of the carbons, the voltage across the arc increases until at a pre determined voltage value the resistance is overcome and sufficient current flows through the shunt coils to energize the same and move the core in a direction opposed to the pull of the series coils. The pull of the shunt coils more, than offsets the decreasing pull of the series coils, thereby lowering the upper car bon slightly, enough to restore the necessary balance and maintain the predetermined length of the arc. This is accomplished by virtue of the fact that as the upper carbon is being lowered, due to the differential action of the two coils, the decreased resistance of the arc causes an increased flow of current in the series coils whereby their pull eventually balances the pull of the shunt coils. This operation takes place upon very slight amperage fluctuations, due largely to the practical elimination of friction and the reduction of the weight to be lifted and of the inertia of the parts to a minimum, with the result that the carbons do not become separated a sufficient distance to break the arc, nor does I the arc flicker, but burns steadily for hours.

To prevent the movement of the hotspots of the are around the points of the carbons, a magnet 23 is provided in series with the carbons for stabilizing the arc. The magnetic field created by the coil tends to blow the arc to the front side of the carbons and retains the same in such position, thereby preventing the objectionable shadows previously referred to.

The magnet coil 23 is so mounted as to permit considerable flexibility in its adjustment. It is mounted on a slotted vertical support 36 by means of a screw 37 whereby it may be raised and lowered. Said member may be swung about a horizontal pivot 38 at the lower end of an arm 39, the upper end of which may be adjusted back and forth in a horizontal slot in an arm 40 by means of a bolt 41, one end of said arm 40 being arranged to turn about a vertical pivot 42 at one end of a slotted arm 43 which latter is adjustable vertically in a slot in a bracket 44, the latter being arranged to swing on a vertical stud 45. With this arrangement the magnet coil may be swung, for example, to the dot-ted line position shown in Fig. 5, to deflect the arc forwardly. However, where a series of arc lamps in a row are employed as in blue print machinery, for example, the arc is influenced by various parts of thestructure so that it may be necessary to adjust the different magnet coils to different relative positions in the case of the various lamps, in order that all of the arcs may be blown toward the front.

As a further refinement in the operation, the shunt coils 25 are shown in Fig. 4 as being connected individually by means of taps 46 to a switch 47 which may be mounted on any convenient part of the frame. lamp is assembled the switch is adjusted so as to utilize'all four of the shunt coils, if

necessary to the proper operation of the de-.

vice. Due to variations in materials it may be necessary to utilize only three or aless i number of the coils in any particular installation and the switch will therefore be adjusted accordingly. It will usually be left undisturbed after the initial adjustment except where variations in line voltage render further adjustment desirable.

lVith the adjustments described it is possible to adjust two or more are lamps so that they will emit light of the same value for considerable intervals of time, even though said lamps are mounted in a row whereby each influences the other.

The provision of individual series and shunt coils is better than the provision of a single coil having both series and shunt l windings for the reason that with the arrangement shown, eddy currents are eliminated and overheating prevented. A further cooling advantage results in the provision of sectional shunt and series coils as the Vhen the eddy currents are substantially eliminated and the ventilation of the individual sections is increased.

Surrounding the operating mechanism is a shield 48 which may be of wire or expanded metal to protect the same against damage and to protect the operator against injury.

The stability of the lamp described herein is dependent on a number of factors. First, friction is substantially eliminated since there are but two areas in frictional engagement in the lamp mechanism, i. e. the small pins and bearings about which the frame turns. It will be seen that the armature does not make contact with the magnet coils but clears the same at all times. \Vith the carbon removed from. the lamp, the mechanism is perfectly balanced and is so sensitive that it will move at the slightest change of arc voltage. Second, the arrangement whereby the sections of the shunt coils may be varied is important as the adjustment of the same by means of the switch permits compensation for variations that necessarily occur within the coils when they are wound and in the metal of the armature itself. This variable shunt coil is of great benefit in balancing the lamp in each particular installation, as the amperage across the arc itself can be changed as this shunt coil is varied, permitting not only the lamp itself to be balanced, but variations in. the line voltage to be compensated for. For example, if three sections of the shunt coil are in circuit, and the upper carbon moves irregularly due to the arc voltage being a little too high, by changing the switch point to include four coils in the circuit, the greater pull created by the extra coil helps to shorten the arc and bring about a lower voltage with a stable condition. The decreased voltage results in an increased amperage, the wattage across the arc remaining the same in all cases.

It is well known that nearly all of the effective light in a direct current are lamp is received from the crater of the positive carbon, and in the case of alternating current considerably more than one-half of the effective light is received from the crater or two hot-spots, one on each carbon. Some authorities state that the ratios are in the case of direct current and over 60% in the case of alternating current. In view of these facts the advantage of having the hot spots confined to the front of the carbons is obvious, and by means of a stable arc the temperature remains substantially constant, thereby insuring light of uniform value for photographic purposes at all times, due to the very slight and unchanging friction and the use of two pivots for the oscillating frame. In this connection, the use of the terms above and below and similar terms are understood to be used in a relative sense without necessarily implying an exact vertical arrangement of the carbons and associated parts. The lamp also operates satisfactorily in inclined position.

Although I have shown certain features of my improvements combined in a single structure, it will be apparent that some of them are capable of use independently of others and that various changes may be made in the design and arrangement of parts illustrated herein without departing from the spirit of the invention.

What I claim is:

1. An arc lamp having an adjustable car bon and a stationary carbon, a fixed open center coil in series with said carbons, a fixed open center shunt coil across the same, a single arcuate core passing through both of said coils, and means for transmitting motion from said core to said adjustable carbon, said core and said means being balanced about a pivotal support, said shunt coil tending to move said core in a. direction to reduce the arc gap, and said series coil opposing such movement whereby fluctuations in voltage and current values due to a slightly increased gap between the carbons will reduce the effectiveness of the series coil 011 the core and permit movement of the latter by the shunt coil in a direction to reducethe gap, thus insuring a stable are.

2. Carbon adjusting mechanism for an arc lamp comprising an armature operatively associated with the adjustable carbon, and balanced to carry only the weight of said carbon, a coil for said armature in series with the two carbons, a differential shunt coil adapted to move said armature in a direction to reduce the arc gap upon an increase in the voltage across the are above normal, said shunt coil comprising a plurality of tapped sections, and a switch for cutting out one or more of said sections from the shunt circuit.

3. An arc lamp comprising alower and an upper carbon, a fixed current responsive coil, a fixed voltage responsive coil and armatures therefor mechanically connected to said upper carbon only, said coils being arranged to act differentially whereby an increase in the length of the arc weakens. said current coil and, above a predetermined value, strengthens said voltage coil, said mechanical connections comprising a support having a single pivoted axis to minimize friction and to provide a balanced arrangement, thus insuring stability of the are.

4. An arc lamp comprising a lower and an upper carbon, a current responsive coil and a voltage responsive coil mechanically connected to said upper carbon only and arranged to act differentially whereby an increase in the length of the arc weakens said current coil and strengthens said voltage coil, said mechanical connections comprising a core and a frame therefor having a single l pair of pivotal supports, said frame and associate parts being normally balanced about said pivotal support when said upper carbon is removed, adjustable magnetic means for blowing the arc to the front of the carbons and means for varying the normal amperage of said are to insure uniform light'from the same.

5. An arc lamp comprising a fixed carbon and an adjustable upper carbon, a ring clutch for the latter, a supporting frame above said carbons, an oscillatable frame pivoted to said supporting frame and connected to said clutch, a group of series coils are ranged radially with reference to said pivoted support and at one side of said oscillatable frame, a group of shunt coils also radially arranged with reference to the same axis, an arcuate core passing through all of said coils, brackets on said oscillatable frame by which said core is carried and a switch for varying the number of shunt coils in circuit.

6. An arc lamp comprising a vertical frame, a rectangular frame, a pair of pivotal supports connecting the two, a curved frame secured to said Vertical frame and having a series of lugs thereon, a plurality of coils each mountedon one of said lugs in radial position with reference to the axis of said pivots, a single are shaped core passing through all of said coils, an adjustable weight at one end of said rectangular frame, a depending link at the other end thereof, a carbon holding clutch secured to said link and a switch connected to certain of said coils. c

In testimony whereof, I have subscribed my name.

7 HAROLD J. BRUNK.

CERTIFICATE or CORRECTION.

Patent No. 1,812,469. Granted June 30, 1931, to

- HAROLD J. BRUNK.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 3, line 83, claim 1, after the word "means" insert the words including a clutch; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 3rd day of November, A. D. 1931.

M. J. Moore, (Seal) Acting Commissioner of Patents.

CERTIFICATE OF CORRECTION.

Patent No. 1,812,469. Granted June 30, 1931, to

- HAROLD J. BRUNK.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 3, line 83, claim 1, after the word "means" insert the words including a clutch; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 3rd day of November, A. D. 1931.

M. J. Moore, (Seal) Acting Commissioner of Patents. 

